OmniCal Calibration & alignment

Workflow

Calibration

• Once the calibration is completed, you can view the point cloud and check the error in pixels, for each projector.

• You may need to adjust the calibration parameters to get the best results, but usually these are chosen automatically.

Alignment

1. Manually align the point cloud with the projection surfaces in the disguise software.

2. Add alignment points to the camera images to line up wireframe views of the projection surfaces with reality.

3. This only needs to be done once as long as cameras or projection surfaces do not move.

4. Re-shape points can also be added to correct the shape of the mesh, this can be thought of as a 3D warp from the cameras point of view.

Example

Calibration

1. Click Calibrate

The system runs the calibration and reports the calibration results in the calibration results widget. The pixel error per camera & projector will be displayed at the bottom of this widget. Values below 1px are considered good, and above 1px usually points to something going wrong in the process.

The generated point cloud will appear in the disguise stage visualiser at this point but will not be aligned to the stage, unless you previously performed an alignment.

Alignment

1. The generated point cloud will be aligned to the stage based on the previously performed simulated calibration. If no simulated calibration has been performed, the point cloud will be un-aligned with the stage.

   There are some automatic options to automatically align the point cloud to the stage. Click Quick Align, and choose Alignment Estimate which is automatic alignment estimation based on point cloud and all projection surfaces.

   Align to plan cameras which is the automatic alignment based on positions of plan cameras.

   Align to plan which aligns to plan cameras and projectors.

   Align to point cloud is useful for alignment using 2D camera reference points. Use this option when you want to apply the current alignment data to the stage.

   If the Alignment assistance tools do not work, proceed to the next step.

2. Manually align the point cloud with the stage using Initial position, Initial rotation and Initial scale settings.

3. Once the point cloud is roughly aligned, you can perform a Quick Align.

1. Left-click Quick Align to open the Quick Align editor.

2. The top two views relate to cameras which can be chosen from the view tab.
   

   The bottom two views relate to the cursor location in the camera view. This is essentially a zoomed in view, for better view finding.

3. Left-click a point on the wireframe.

4. Drag it to the corresponding point in the image. Do the same for the corresponding point in the second camera view.

5. Repeat this process for a minimum of three points.

1. Red point means this point is not being used as part of the alignment, but has been added to the view.

2. Yellow means it has been aligned in the current camera, but it is not being used in the calculations.

3. Orange means it has been aligned in a different camera.

4. Green means it has been aligned in both cameras and is being used in the calculation.

5. Selected points flash, and you can use the arrow keys to move them around.

6. When points are selected, use SHIFT + arrow keys to move the point around & hold CTRL & left-click for fine control.
   

Alignment re-shape

If the proportions of the model are correct, the alignment should fit perfectly. If the proportions are not correct, you will need to perform a reshape. This can be done by holding SHIFT and left-clicking a point which will turn it into a reshape point. Left-clicking the point again will turn it back to a alignment point. A reshape does not use the point cloud, and simply adjusts the proportions of the model to match.

Multi-screen alignment

• The master screen should be aligned first.

• It not moved on the stage. It acts as a registration point for other screens. Reshaping or scaling of the Master screen will therefore affect all other screens.

• When aligning secondary screens, they will be moved to the correct position relative the Master screen.

• Its best to choose a screen that does not move, for a master screen.

Mesh deform

If the depth of the mesh in the disguise software does not match the real world object, it will require mesh deforming. Mesh deform will deform the mesh to match the point cloud.

It is a good idea to try the default settings for mesh deform first, to see if you get a good deform. If not, proceed to tweak the settings as required.

You can quickly preview Mesh deform results by changing the Point Cloud visualisation mode to Deform in the OmniCal calibration editor. The results are updated in real-time so you can try out different deform settings using this. The lines indicate where each point on the mesh would be moved to.

1. To perform a Mesh deform, click Mesh deform from the Alignment tab of the Plan editor

2. Select the screen you wish to deform by left-clicking the screen property in the deform editor.

3. Left-click Deform